4.1. Direct activity against pathog

4.1. Direct activity against pathogens
Direct activity of chitosan against viruses and viroids has been shown to vary according to
molecular weight [21]. However, none of the studies that investigated this effect has clearly proven the
ability of chitosan in completely inactivating viruses or viroids. Most literature i.e., [21] reported on
the inactivation of replication, which lead to the stoppage of multiplication and spread. This could be
linked to the fact that upon penetration into plant tissues, chitosan nanoparticles tightly bind nucleic
acids and cause a variety of damages and selective inhibitions. For instance, the selectively exerted
inhibition could inactivate the synthesis of essential mRNA encoded by various genes required for
important metabolic and infectious processes of the virus or viroid. These properties have been largely
explored in gene therapy and gene silencing [20,67].
Against, bacteria, fungi, oomycetes and other pests, it seems that chitosan is likely to operate
indirectly via other means such as the enhancement of host resistance. However, a number of studies
have shown that chitosan, at defined concentrations, presents antimicrobial properties [33,68,69]. For
instance, chitosan was reported to exert an inhibitory action on the hyphal growth of numerous
pathogenic fungi, including root and necrotrophic pathogens, such as Fusarium oxysporum, Botrytis
cinerea, Monilina laxa, Alternaria alternata and Pythium aphanidermatum [63,70–76] besides
inhibiting spore germination in some of them [18].
Chitosan is often used in plant disease control as a powerful elicitor rather than a direct
antimicrobial or toxic agent. Its direct toxicity remains dependent on properties such as the
concentration applied, the molecular weight, degree of acetylation, solvent, pH and viscosity [77,78].
The degree of acetylation defines the sites with which nucleophilic groups could react and viscosity
provides an environment that could extend the duration and intensity of reactions.

Results (Indonesian) 1:

4.1. langsung kegiatan terhadap patogen Kegiatan langsung chitosan terhadap virus dan viroids telah terbukti bervariasi menurutberat molekul [21]. Namun, tidak ada studi yang menyelidiki efek ini telah jelas terbuktikemampuan chitosan di benar-benar inactivating virus atau viroids. Kebanyakan sastra yaitu, [21] dilaporkan padainaktivasi replikasi, yang mengakibatkan penghentian perkalian dan menyebar. Ini bisa menjaditerkait dengan fakta bahwa berdasarkan penetrasi ke dalam jaringan tanaman, partikel nano chitosan erat mengikat nukleatasam dan menyebabkan sejumlah kerusakan dan selektif hambatan. Sebagai contoh, selektif diberikaninhibisi dapat menonaktifkan sintesis penting mRNA dikodekan oleh berbagai gen yang diperlukan untukpenting proses metabolisme dan infeksi virus atau viroid. Properti ini telah sebagian besardieksplorasi di terapi gen dan gen membungkam [20,67]. Melawan, bakteri, jamur, oomycetes dan hama lainnya, tampaknya chitosan mungkin untuk beroperasisecara tidak langsung melalui cara lain seperti peningkatan resistensi host. Namun, beberapa studitelah menunjukkan chitosan, pada konsentrasi didefinisikan, sifat antimikroba hadiah [33,68,69]. UntukMisalnya, chitosan dilaporkan untuk mengerahkan tindakan penghambatan terhadap pertumbuhan hyphal banyakjamur patogen, termasuk patogen akar dan necrotrophic, seperti Fusarium oxysporum, Botrytis cinerea, Monilina laxa, Alternaria alternata dan Pythium aphanidermatum [63,70-76] Selain menghambat spora dalam beberapa dari mereka [18].Chitosan sering digunakan dalam pengendalian penyakit tanaman sebagai elicitor kuat daripada langsung agen antimikroba atau beracun. Toksisitas langsung tetap tergantung pada sifat sepertikonsentrasi diterapkan, berat molekul, tingkat acetylation, pelarut, pH dan viskositas [77,78].Tingkat acetylation mendefinisikan situs dengan kelompok nukleofilik dapat bereaksi dan viskositasmenyediakan lingkungan yang dapat memperpanjang durasi dan intensitas reaksi.