Pengujian Lokasi Patogen dan Penlaran Patogen Terbawa Benih

Salah satu faktor penyebab kurang maksimalnya produksi suatu  komoditas pertanian yaitu karena adanya penggunaan benih  yang tidak bermutu. Diantaranya  faktor yang menentukan mutu benih adalah kesehatan benih yang ditentukan oleh ada atau tidaknya mikroorganisme terbawa benih, seperti cendawan, nematoda, bakteri, atau virus (Badan Karantina.2002). Benih yang sehat sangat penting dalam produksi tanaman pertanian karena benih merupakan titik awal untuk mendapatkan tanaman yang sehat.  

Oleh karena itu agar benih terhindar dari kontaminan dan patogen maka pentingya pengetahuan lokasi patogen yang terdapat pada benih, dan cara penularan patogen terbawa menih. Patogen dalam benih dapat berada pada kulit biji, kotiledon, dan embrio. Pada praktikum pengujian lokasi patogen terbawa benih dilakukan pada dua komoditas yaitu kedelai dan kacang tanah. Pada kulit biji patogen yangmendominasi biasanya dari golongan cendawan sedangakan golongan virus biasanya terdapat pada embrio. Penularan patogen terbawa benih uga dapat dilakukan dengan menginokulasikan patogen tersebut pada tanaman indikator. Kemudian tanaman yang diinokulasi setelah diinkubasi akan menunjukan gejala.  

Pengujian patogen terbawa benih pertama benih di cuci baik kedelai maupun kacang tanah, dengan menggunakan kloroks 1% selama 1menit. Kemudian benih diangkat dan dicuci dengan menggunakan air steril selam 15 menit. Kemudian benih di angkat dengan menggunakan pinset dan ditiriskan pada kertas hisap. Kemudian benih dipisahkan bagian-bagiannya untuk mendapatkan kotiledon, kulit biji, dan embrio. Setelah itu, benih diplating kedalam cawan petri yang sebelumnya sudah berisi kertas blotter. Kemudian diinkubasi selama seminggu pada suhu ruang dan diamati jenis patogen yang muncul. 

Penularan patogen terbawa benih prtama untuk penularan virus terbawa benih yang diinokulasikan pada tanaman Nicotiana sp.yaitu pertama-tama benih atau daun digerus dalam Buffer fosfat pH 7 dengan rasio 1:10, kemudian daun dibubuhi carborondum 600 mesh untuk dilakukan inokulasi secara mekanis. Kemudian daun yang telah diinokulasi dibilas dengan air steril dan diinkubasi selama satu minggu dan diamati gejala yang muncul. Pada penularan bakteri terbawa benih, pertama-tama biakan Xantomonas oryzae dibasahi dan diaduk. Kemudian dicampurkan dengan air sterilhingga volumenya 50 ml, kemudian rendam gunting pada larutan tersebut, setelah itu potong daun padi dengan gunting yang sudah di rendam. Kemudian diinkubasi selama satu minggu dan doiamati gejala yang muncul. 

Berdasarkan hasil pengamatan patogen terbawa benih baik pada benih kedelai maupun kacang tanah, patogen dapat ditemukan pada kulit biji, kotiledon, dan embrio. Patogen yang ditemukan berasal dari golongan cendawan. Pada penularan bakteri terbawa benih masa inkubasi terjadi pada hari ke2 dan ke 4, gejala yang teramati yaitu kresek yang disebabkan oleh patogen Xantomonas oryzae. Pada penularan virus terbawa benih gejala yang teramati yaitu lesio lokal yang ditandai dengan adanya nekrosis pada awal munculnya gejala.

Metode Bioteknologi "PCR"

Polymerase Chain Reacton (PCR) adalah suatu teknik sintesis dan amplifikasi DNA secara in vitro. Teknik ini pertama kali dikembangkan oleh Karry Mullis pada tahun 1985. Teknik PCR dapat digunakan untuk mengamplifikasi segmen DNA dalam jumlah jutaan kali hanya dalam beberapa jam. Dengan diketemukannya teknik PCR di samping juga teknik-teknik lain seperti sekuensing DNA, telah merevolusi bidang sains dan teknologi khususnya di bidang diagnosa penyakit genetik, kedokteran forensik dan evolusi molekular.

Prinsp- prinsip PCR adalah komponen- komponen yang diperlukan pada proses PCR adalah templatDNA; sepasang primer, yaitu suatu oligonukleotida pendek yang mempunyai urutan nukleotida yang komplementer dengan urutan nukleotida DNA templat; dNTPs (Deoxynucleotide triphosphates); buffer PCR; magnesium klorida (MgCl2) dan enzim polimerase DNA. 

Proses PCR melibatkan beberapa tahap yaitu: (1) pra-denaturasi DNA templat; (2) denaturasi DNA templat; (3) penempelan primer pada templat (annealing); (4) pemanjangan primer (extension) dan (5) pemantapan (postextension). Tahap (2) sampai dengan (4) merupakan tahapan berulang (siklus), di mana pada setiap siklus terjadi duplikasi jumlah DNA.  PCR adalah suatu teknik yang melibatkan beberapa tahap yang berulang (siklus) dan pada setiap siklus terjadi duplikasi jumlah target DNA untai ganda. Untai ganda DNA templat (unamplified DNA) dipisahkan dengan denaturasi termal dan kemudian didinginkan hingga mencapai suatu suhu tertentu untuk memberi waktu pada primer menempel (anneal primers) pada daerah tertentu dari target DNA. 

Polimerase DNA digunakan untuk memperpanjang primer (extend primers) dengan adanya dNTPs (dATP, dCTP, dGTP dan dTTP) dan buffer yang sesuai. Umumnya keadaan ini dilakukan antara 20 – 40 siklus. Target DNA yang diinginkan (short ”target” product) akan meningkat secara eksponensial setelah siklus keempat dan DNA non-target (long product) akan meningkat secara linier seperti tampak pada bagan di atas.

Keunggulan Pengendalian Hayati

            Secara teknis, pengendalian hayati lebih unggul dibandingkan pengendalian dengan cara kimiawi karena selain efektif dan efisien juga ramah lingkungan. Perkembangan hasil penelitian tentang berbagai agensia hayati yang bermanfaat untuk mengendalikan berbagai patogen pada tanaman, sebenarnya sudah cukup menggembirakan walaupun masih sedikit yang dapat digunakan secara efektif di lapangan. Dampak positif dari pengendalian hayati penyakit tanaman diperoleh secara berangsur-angsur dan berkesan lambat dibandingkan penggunaan pestisida.

            Cendawan endofit merupakan salah satu agen pengendali hayati yang saat ini mulai banyak dikenal oleh masyarakat. Cendawan Endofit dapat diartikan sebagai simbiosis mutualistik dengan batang, pohon, daun, rumput atau herba sebagai inangnya. Hampir semua tanaman tingkat tinggi dapat mengandung beberapa cendawan endofit yang mampu menghasilkan senyawa biologi atau metabolit sekunder. Beberapa kajian terhadap cendawan endofit terbukti memiliki potensi ekonomi yang cukup tinggi, baik sebagai bahan baku obat, maupun penghasil senyawa bioaktif lain yang bermanfaat dalam bidang pertanian (Lestari, 2011).

            Mikroba endofit merupakan mikroba yang hidup di dalam jaringan tanaman, tanpa menimbulkan gejala penyakit pada tanaman inangnya. Hubungan antar mikroba endofit dengan tanaman inangnya merupakan suatu bentuk hubungan simbiosis mutualisma, yaitu sebuah bentuk hubungan yang saling menguntungkan. Mikroba endofit dapat memperoleh nutrisi untuk melengkapi siklus hidupnya dari tanaman inangnya, sebaliknya tanaman inang memperoleh proteksi terhadap patogen tumbuhan dari senyawa yang dihasilkan mikroba endofit (Prihatiningtias, 2005 dalam Haniah, 2008).

            Asosiasi cendawan endofit dengan tanaman inangnya digolongkan dalam dua kelompok yaitu mutualisme konstitutif dan induktif. Mutualisme konstitutif merupakan asosiasi yang erat antara cendawan dengan tumbuhan terutama rumput-rumputan. Pada kelompok ini cendawan endofit menginfeksi ovula (benih) inang, dan penyebarannya melalui benih serta organ penyerbukan inang. Mutualisme induktif adalah asosiasi antara cendawan dengan tumbuhan inang yang penyebarannya terjadi secara bebas melalui air dan udara. Jenis ini hanya menginfeksi bagian vegetatif inang dan seringkali berada dalam keadaan metabolisme inaktif pada periode yang cukup lama (Carol, 1988 dalam Haniah, 2008). 

            Cendawan endofit yang tidak menyebabkan gejala penyakit diteliti lebih dari 300 spesies tanaman, sebagian besar dari kelas Ascomycetes (Carol, 1988 dalam Istikorini, 2008). Beberapa cendawan yang tergolong endofit adalah Acremonium, Fusarium, Trichoderma, Colletotrichum, Gliocladium, Alternaria, Beauveria, Penicillium, Mucor dan Phylosticta (Amin et al, 1997 dalam Istikorini, 2008).  Pada akar Lepanthes (Orchidaceae) ditemukan cendawan endofit Colletotrichum, Aspergillus, Penicillium, Pestalosia dan Phoma (Bayman et al, 1997 dalam Istikorini, 2008).

            Potensi cendawan endofit sebagai agen pengendali hayati, antara lain karena endofit hidup dalam jaringan tanaman sehingga dapat berperan langsung dalam menghambat perkembangan patogen dalam tanaman (Niere, 2002 dalam Istikorini, 2008). Mikroba endofit dapat melindungi tanaman inang dari serangan patogen dengan senyawa yang dikeluarkannya, berupa senyawa metabolit sekunder yang merupakan senyawa bioaktif dan dapat berfungsi untuk membunuh patogen (Prihatiningtias, 2011). Cendawan endofit dalam tanaman diketahui dapat menyebabkan berkurangnya kerusakan pada sel atau pada jaringan tanaman, meningkatkan kemampuan bertahan hidup dan fotosintesis sel jaringan tanaman yang terinfeksi patogen tular tanah (Sinclair & Cerkauskas, 1996 dalam Istikorini, 2008).

            Keberadaan cendawan endofit dapat ditemukan baik pada tanaman pertanian maupun rumput-rumputan (Faeth, 2002 dalam Istikorini, 2008). Kolonisasi cendawan endofit dapat meningkatkan senyawa fenol dalam inang, Senyawa fenol dapat menghambat patogen secara langsung atau dengan produk oksidasinya dan juga dengan meningkatkan perubahan metabolik kompleks seperti senyawa yang dapat membentuk barrier pertahanan (Agrios, 1997; Gazoni & Stegman, 1997 dalam Istikorini, 2008).

            Mekanisme penghambatan cendawan endofit terhadap patogen dapat secara langsung dengan mekanisme antagonis dan secara tidak langsung dengan mekanisme ketahanan terinduksi. Perlindungan tanaman dengan ketahanan terinduksi didasarkan pada rangsangan mekanisme ketahanan oleh adanya perubahan metabolik yang memungkinkan tanaman untuk lebih mengefektifkan ketahanannya. Diperkirakan ketahanan terinduksi dapat berkembang apabila sel-sel tanaman mampu menghasilkan enzim-enzim baru yang mengaktifkan gen tanaman yang bertanggung jawab dalam mekanisme ketahanan tanaman tersebut (Agrios, 1997 dalam Istikorini, 2008).

            Penggunaan cendawan endofit dari kelas Actinomycetes sebagai agen pengendali hayati mempunyai keuntungan yaitu kemampuannya untuk menghindari persaingan dengan sebagian besar mikroorganisme tanah dan rhizosfer karena cendawan dari kelas Actinomycetes ini hidup di dalam jaringan akar tanaman (Coombs & Franco, 2003 dalam Anugrahwati, 2011). Keberadaannya di dalam jaringan hidup tanaman selama pertumbuhan tanaman memungkinkan induksi resistensi sistemik yang dapat memberikan perlindungan yang lebih baik pada tanaman (Sturz et al, 2000; Siddiqui & Shaukat, 2002 dalam Anugrahwati, 2011).

            Salah satu contoh penggunaan cendawan endofit adalah untuk mengendalikan penyakit VSD pada tanaman kakao di pulau Sulawesi. Penelitian penggunaan musuh alami untuk mengendalikan penyakit VSD belum pernah dilakukan baik di Sulawesi, maupun di negara lainnya. Pengendalian biologi  memungkinkan untuk dilakukan, namun harus menggunakan musuh alami yang bersifat endofit untuk bisa berkompetisi di dalam jaringan tanaman. O. theobromae menginfestasi jaringan xylem sehingga bisa bertahan lama dalam jaringan tanaman. Sejumlah musuh alami yang endofit ini telah diidentifikasi pada tanaman kakao di Panama dan Brazil seperti Colletotrichum, Botryospharia, Nectria dan Trichoderma (Mejia et al., 2004; Samuel, 2004 dalam Rosmana, 2005). Di Sulawesi sendiri, identifikasi cendawan endofit sedang dilakukan dan ada beberapa isolat Trichoderma ditemukan pada biji kakao. Cendawan endofit di Panama dan di Brazil digunakan untuk mengendalikan penyakit busuk buah yang disebabkan Phytophthora sp. dan Moniliophthora serta penyakit sapu setan yang disebabkan oleh cendawan Crinepellis perniciosa. Penggunaan cendawan endofit ini mungkin dapat dilakukan melalui daun-daun terserang atau melalui penginfusan (Rosmana, 2005).         

Sumber

A. Anugrahwati, 2011, Aktifitas Actinomycetes Endofit Sebagai Bionematisida         Terhadap Meloidogyne Javanica Activity of Endophytic Actinomycetes as         Bionematicide against Meloidogyne javanica, dikutip dari    http://fp.unram.ac.id/data/Profil%20Jurusan/Jurnal%20Crop%20Agro/Jurnal%    20Crop%20Agro%20Vol%201%20No%202/6.DwiRatnaAnugrahwati-114-     122.pdf, diakses pada tanggal 29 November 2011.

B. Haniah, 2008, Isolasi Jamur Endofit Dari Daun Sirih (Piper betle L.) Sebagai       Antimikroba Terhadap Escherichia coli, Staphylococcus aureus DAN Candida          albicans, dikutip dari             http://lib.uinmalang.ac.id/files/thesis/fullchapter/03520054.pdf, diakses pada        tanggal 21 November 2011.

C. Istikorini, 2008, Potensi Cendawan Endofit untuk Mengendalikan Penyakit          Antraknosa Pada Cabai (Capsicum annuum L.), dikutip dari             http://repository.ipb.ac.id/bitstream/handle/123456789/40844/Bab%201%202       008yis.pdf?sequence=3, diakses pada tanggal 21 November 2011.

D. Lestari, C.E, 2011, Cendawan Endofit, dikutip dari       http://epilestari.blogspot.com/2011/03/cendawan-endofit.html, diakses pada             tanggal 29 November, 2011.

D. Prihatiningtias, 2011, Prospek Mikrobia Endofit Sebagai Sumber Senyawa Bioaktif,       dikutip dari http://mot.farmasi.ugm.ac.id/artikel-55-prospek-mikroba-endofit-       sebagai-sumber-senyawa-bioaktif.html, diakses pada tanggal 23 November         2011.

E. Rosmana Ade,  2005, Vascular Streak Dieback (VSD): Penyakit Baru Pada          Tanaman Kakao Di Sulawesi, Prosiding Seminar Ilmiah dan Pertemuan Tahunan PEI dan PFI XVI Komda Sul-Sel, dikutip dari     http://www.infodiknas.com/185-vascular-streak-dieback-vsd-penyakit-baru-          pada-tanaman-kakao-di-sulawesi/, diakses pada tanggal 9 Maret 2012.

Charlotte Linlin "Big Mom One Piece"

Charlotte Linlin, also known as Big Mom, is the captain of the Big Mom Pirates and one of the Yonko. She was the last Yonko to be named. Her epithet was first revealed just after the Battle of Marineford by Eustass Kid, and her real name was first mentioned by Pappug in the Fishman Island Arc. Big Mom has only been seen partially from the shadows, but it is clear that she is an incredibly large and obese woman whose face appears to be larger than her body. She also has a very wide grin, long curly hair, large bulging eyes, and a round nose and cheeks. Her dress code seems to consist of a pink dress with red polka dots and high-heels.

In all of her appearances, she's always seen drooling a large amount of saliva. She was also shown to have a ring on the thumb of her left hand.
“     I wonder if we can explain the situation? She is like a monster who would destroy a whole country for sweets! One of the Four Emperors... Big Mom!     ”
— Minister of the Left on Charlotte Linlin

She loves sweets as she makes all the islands under her protection pay her in whatever kind of candy they can produce. She seems to be obsessed with them to the point that she bases her likes and hates from them and would destroy a country all for the sake of sweets. In spite of that though, she did not lose her control when Luffy claimed to have eaten all of her candy. Although she does not seem greedy, Big Mom seems to have somewhat of a capitalist mindset. She also refers herself as "ore" (おれ?), a masculine way of saying "I", instead of the feminine "watashi" (私?) that most other females use.

If anything, she strongly believes that a Pirate must accept no compromise for something they want, and without any delays. Pappug thinks she is protecting Fishman Island with a business perspective, since the deals made with the candy do qualify as racketeering, although she seems to prioritize sweets over money and treasure. From her point of view, pirates do not accept compromises as she even refused a proposal of money to repair two of her ships and in turn, double the amount of candy for a simple delay of two weeks.

It also appears that she is quite ruthless as she decided to burn a country down when they failed to make their sweet payment, disregarding any reason for the failure, under the reason that she hates people who cannot keep their promises. The Minister of the Left was struck with apprehension and fear when it was realized her payment could not be made that month. She is infamous for decimating islands over slight infractions, and is very voracious and is almost always seen drooling to the point that, when Luffy offered her treasure, she believed that he expected her to eat it in place of the candy. It appears she may even eat some of her own subordinates if hungry enough, showing clear signs of cannibalism.

Her subordinates call her "Mama" (ママ Mama?), and most seem to be afraid of her. Also, she is willing to eat her underlings when she is hungry, showing she doesn't seem to care for their well-being very much. So far, only the unnamed three-eyed girl and Bobbin appear to be unafraid of her. Bobbin even had a friendly chat with Big Mom after returning to her at Whole Cake Island.

Given her capitalist mindset, Big Mom only seems to impart protection upon her chosen territories for as long as they can meet the demanded candy tribute and will not hesitate to have them destroyed if there is even a chance that they will not be able to pay. Also her definition of "protection" seems to just mean from pirates, as her crew stated that the rebellion on Fishman Island was none of their concern.

When Big Mom sent her underlings to collect the candy from Fishman Island, Luffy talked to her via a Den Den Mushi claiming that he is responsible for the lack of candy. However, Big Mom easily saw through his lie. She refused to take the treasure that Luffy offered in place of candy but admired the Supernova for standing up to her; and so she decided to target Luffy instead of Fishman Island. In response, Luffy notes that leaving Fishman Island under the protection of someone who would destroy it on a whim was out of the question. Thus, he declared a war saying that he would defeat her in the New World and that he would make Fishman Island his own territory.

As one of the Yonko, Big Mom is one of the four most powerful pirates in the world. She has a mouth large enough to devour an entire person. Moreover, when she becomes hungry, she starts to salivate her stomach acids, which seem to be even more corrosive than those of a regular person. It was also stated by the Gorosei that she is one of the few people capable of stopping Teach.

While under Big Mom's protection, Fishman Island is protected from pirate attacks, indicating a powerful influence similar to that of the late Whitebeard. After the Battle of Marineford and the death of Whitebeard, Fishman Island was once again vulnerable to pirate attacks and the slave trade. Big Mom then decided to protect it in Whitebeard's place with candy as payment, thus leading to the Candy Factory's creation. The Sun Pirates would also join her crew for protection due to Jinbe having resigned his position. Even though she kept Fishman Island safe from pirate attacks, she does not actually care for the island's well-being as she did nothing to protect it from the New Fishman Pirates' uprising and her "protection" is actually holding the island hostage in a manner similar to the Arlong Pirates, threatening to destroy it if they miss a monthly tribute.

After the battle between the Straw Hat Pirates, the Ryugu Kingdom and the New Fishman Pirates concluded, she sends two of her subordinates to collect the monthly candy tribute, unaware that the factory was destroyed. The Minister of the Left then reveals that Big Mom would be infuriated with the lack of payment, possibly even destroying Fishman Island to get the candy.

Big Mom first appears on Whole Cake Island. She is excited for a tea party coming up in four days as that means she will soon be able to eat the candy from Fishman Island. She asked some of her subordinates if they were excited as well. Even though they agreed, Big Mom apparently ate them, saying they would continue their excitement in her stomach. Shortly thereafter, Bobbin announces himself and Big Mom asks how his job of destroying an island that failed to make its monthly candy tribute went, to which he responds everything went up in flames. Big Mom is pleased, commenting that the baked sweets from that country were delicious, and that the island must have smelled delicious as it was burned down, saying the loss of that candy is a shame. She then comments that she does not like people who do not keep their word, especially when candy is involved. When she learned that Fishman Island could not make their monthly payment, she ordered for a call to be placed to the island at once. When the call goes through to the island, Pekoms and Tamago are too nervous to answer it, so Luffy does.

When Luffy tells her who he is, she remembers his actions in Marineford and his relation to Garp. Luffy then tells her he ate all ten tons of the candy. Big Mom calls him on his lie, but Luffy tells her he speaks the truth. When Luffy offered her their treasure as collateral, she was offended saying she would only take candy. Baron Tamago then tells her that Eustass Kid sank two of their ships and they need money to cover the damages, so they should take the gold and allow the island two weeks to recover and make new candy. Big Mom is then insulted further still, saying that pirates do not compromise. She then tells Tamago that she has become interested in Luffy, and will change target of her wrath from Fishman Island to Luffy alone. Luffy then tells her that it is too dangerous to leave her in charge of the Fishman Island and he will defeat her when they meet in New World. Luffy then declares he will make Fishman Island his territory when he defeats her. Big Mom's face can only twitch at Luffy's words. 

to be continued...

About Yonko "One Piece"

The Yonko are the four most notorious and most powerful pirate captains in the world (by the World Government), but are neither allies nor enemies of one another, preferring to remain autonomous under most circumstances. These four individually reside within the second half of the Grand Line (known as the "New World"), exerting impressive influence/control over dozens of other pirate crews and self-governing islands.

In the decisive Battle of Marineford, Whitebeard, one of the Yonko, met his end towards the climax of the Whitebeard War. Blackbeard, his assassin, subsequently usurped his position. Shanks, another member of the Yonko, arbitrated a ceasefire to end the aforementioned war.

As an entity, the Yonko are one of the three great powers of the world, the others being the Shichibukai and Marines. Their strength and influence are such that they live quite literally as though they are emperors, doing mostly as they please. Individually, they are considered to be the most powerful pirates in the world, as well as having a powerful crew. Because of their power, they can declare chosen locations as their own; the mere declaration is often enough for others, both Marines and pirates alike, to acknowledge their authority. In fact, in the New World, they each have a territory that they govern. These territories benefit from the protection the emperors provide, keeping the borders safe from any faction that might want to invade them. It is only with the combined efforts of the Marines and the Shichibukai, as well as the distrust among them, that keeps their power in check. During the Battle of Marineford, the Marines and Shichibukai needed to fight together to engage just one of the Yonko and his crew.

The Yonko themselves are not allied together as a coalition compared to the Shichibukai and follow their own individual paths. The possibility of two or more of the Yonko forming an alliance is enough of a threat to cause the World Government to panic, as seen when the World Government attempted unsuccessfully to prevent a meeting between Shanks and Whitebeard at one point in the series. The World Government feared that the two Yonko may unite together and create a stronger threat. A war between two of the Yonko is considered an epic crisis, as Shanks' interception of Kaido's advancement on Whitebeard had taken the Marines by shock and awe, putting the World Government in a "cold sweat" as stated by one of the Marines.

They can motivate others to become pirates, such as Shanks inspiring Luffy. On top of this, the influence these pirates have over others is far greater than any other noted group. With one declaration, the slave trade and pirate attacks on Fishman Island stopped after the island was declared to be under Whitebeard's control.

After the timeskip Trafalgar Law cited that there are only two methods of surviving in the New World, and that is to be protected serving under the umbrella of a Yonko's dominion or to constantly oppose their authority. At least Teach and Kaido are both gaining influence and strength in the form of amassing Devil Fruit powers, both in their own unorthodox methods. Because of their immense power, it is necessary for factions aiming to oppose them to first strike an alliance with other factions in order to bring the Yonko down. The first of the Yonko to be introduced was Shanks who visited Luffy's hometown ten years before the story began. It is unknown if the Yonko existed at this point of time. The second was Whitebeard, one of the only two men to tie in a fight with Gol D. Roger, the Pirate King. Whitebeard was also later announced as the strongest man in the world upon Roger's death. Some of the Shichibukai fought the Yonko in the past; Shanks and Dracule Mihawk frequently dueled in their younger days, Gekko Moriah fought Kaido, and Crocodile fought Whitebeard.

All of the Yonko seem to have strong fleets, including huge ships and elite crewmen. All Yonko have traveled to the New World at some point in their past, where they are currently locked in stalemate, unable to progress any further into the Grand Line. This is a product of the combined efforts of both the Marines and Shichibukai, as well as the presence of the other Yonko in the Grand Line. Until recently, the World Government has been fine with the world powers remaining as they are. With the Yonko stuck in a deadlock situation, this allowed the world to remain stable. However, with the absence of Crocodile, defeated at the hands of the Straw Hat Pirates, the World Government was alarmed that two of the Yonko, Shanks and Whitebeard, arranged to meet each other. Later, with Enies Lobby in ruins, the Marines saw another defeat in the New World when a blockade failed to prevent the two from meeting.

Shanks vs. WhitebeardShanks and Whitebeard clash.

Fearing the two crews might form an alliance, the World Government anxiously waited to know the outcome of the meeting. After Shanks meets with Whitebeard, his presence upon boarding the ship causes a majority of the crew to collapse. He shares sake from his hometown in a token of friendship with Whitebeard as he brings him a grave warning. Shanks tells him that he believes the days of Whitebeard as the strongest pirate are coming to an end, warning him of the new era to come. With Marshall D. Teach making his advance to prominence and he will depose Newgate from his throne. Whitebeard stubbornly refuses Shanks' warning and the two clash. Upon the collision of their swords, the sky seemingly splits in half to the horror of both crews and their members. Afterwards the two depart and Whitebeard continues towards Marineford. In an attempt to rescue his 2nd Division Commander, Portgas D. Ace, Whitebeard attacked Marineford summoning all of his forces from the New World. Kaido attempted to attack Whitebeard; however, he was intercepted by Shanks. During this battle against the Marines, Whitebeard revealed how debilitated he had become over the last two decades, and that he continues to suffer more critical damage from his adversaries in his weakened state. During his battle he destroyed most of Marine Headquarters. He was successfully able to defeat two large Giants with ease and withstood the combined efforts of the three Admirals. He was able to help free Ace and defeat Admiral Akainu after he executed Ace.

Red-hair at marinefordShanks with his crew arrive and bring the war to a close

Remaining at Marineford alone to resolve the conflict with the Marines, Whitebeard was ambushed and ultimately perished at the hands of the Blackbeard Pirates, leaving only three Yonko. Shortly afterwards, Shanks arrived at Marineford with his crew. His presence rescued the remaining allies of Whitebeard and brought the war to an end. Shanks challenged Blackbeard, to which he turned down before escaping with his crew. According to Eustass Kid, due to Whitebeard's death, the Yonko have now been reduced to three, and the balance of the Three Great Powers has collapsed, which led to chaos around the world. Indeed, islands that were once under Whitebeard's protection, such as Fishman Island and Foodvalten, were under attack by pirates.

Some time after the war, X Drake arrived at an island belonging to Kaido, which is stated to be one of the Yonko's favorites. Upon asking "Iron Boy" Scotch, if attacking him would gain Kaido's attention, Scotch replied with the answer: "Yes". Drake changed into his dinosaur form and began attacking the cyborg. Also, the Gorosei hypothesized that Blackbeard was the pirate closest to obtaining the vacant position in the Yonko due to his possession of two Devil Fruit abilities and having complete knowledge about Newgate's sphere of influence. After the death of Whitebeard, Big Mom took over as protector of Fishman Island in exchange for Fishman Island paying a large amount of candy to the Yonko every month. When the candy factory was demolished during the uprising of the New Fishman Pirates, Fishman Island might provoke Big Mom's wrath since the island does not have enough candy for the tribute. Monkey D. Luffy has pledged that he will claim Fishman Island as his protectorate by defeating Big Mom. Teach has also usurped Whitebeard's position as the fourth Yonko, as the Gorosei predicted, having managed to conquer most of Whitebeard's former territory and becoming stronger by hunting down powerful Devil Fruit users and taking their abilities after killing them.

According to Caesar Clown, Kaido has assembled a battalion of Zoan Devil Fruit users using SMILEs provided by Donquixote Doflamingo. During the events of the Punk Hazard Arc, Trafalgar Law offered Monkey D. Luffy an alliance to depose Kaido, to which Luffy agreed, but also insinuated that he would overthrow all four. Eustass Kid, Basil Hawkins and Scratchmen Apoo also came to an agreement and formed an alliance. When Kid saw that Luffy and Law had formed their own alliance, Kid was sure that they were also targeting a Yonko and he wondered who they were targeting.

to be continued... :)