Sequencing wild and cultivated cassava and related species reveals extensive interspecific hybridization and genetic diversity

Cassava (Manihot esculenta) provides calories and nutrition for more than half a billion people. It was domesticated by native Amazonian peoples through cultivation of the wild progenitor M. esculenta ssp. flabellifolia and is now grown in tropical regions worldwide. Here we provide a high-quality genome assembly for cassava with improved contiguity, linkage, and completeness; almost 97% of genes are anchored to chromosomes. We find that paleotetraploidy in cassava is shared with the related rubber tree Hevea, providing a resource for comparative studies. We also sequence a global collection of 58 Manihot accessions, including cultivated and wild cassava accessions and related species such as Ceará or India rubber (M. glaziovii), and genotype 268 African cassava varieties. We find widespread interspecific admixture, and detect the genetic signature of past cassava breeding programs. As a clonally propagated crop, cassava is especially vulnerable to pathogens and abiotic stresses. This genomic resource will inform future genome-enabled breeding efforts to improve this staple crop

Relações entre o teor de fenóis totais e o ciclo das galhas de Cecidomyiida e em Aspidosperm a spruceanum Müll. Arg. (Apocynaceae) Relationships between phenolic contents and a Cecidomyiidae gall cycle in Aspidosperma spruceanum Müll. Arg. (Apocynaceae)

Alterações morfológicas detectadas em diversas espécies vegetais em função da indução de galhas são comumente acompanhadas de mudanças químicas importantes para o estabelecimento e manutenção do sistema galhador-planta hospedeira. O estudo da variação do teor de fenóis totais e sua relação com o desenvolvimento das galhas no sistema Aspidosperma spruceanum-Cecidomyiidae foi realizado ao longo de um ano, no qual foram detectados pelo menos dois ciclos de vida dos insetos indutores. O nível de infestação foliar foi alto, atingindo 87%, e os Cecidomyiidae tiveram a região internervural como sítio preferencial de oviposição. A variação sazonal no conteúdo de fenóis totais nas amostras de folhas sadias e galhadas foi primariamente relacionada às condições abióticas e muito embora este teor tenha atingido o máximo de 10 mg EAT g-1, indicando um ambiente químico celular não favorável à indução e a sua sobrevivência, o indutor de A. spruceanum supera esta barreira química, podendo ainda ser favorecido pela proteção contra inimigos naturais propiciada pelos fenólicos.<br>Morphological alterations detected in several plant species due to gall induction are commonly followed by chemical changes fundamental to the establishment and maintenance of the host plant-gall maker system. The study of phenolic contents variation and its relation to gall development in Aspidosperma spruceanum-Cecidomyiidae system through a year-time detected two insect life cycles. The level of infestation was high, getting up to 87%, and the Cecidomyiidae preferentially oviposited in internervural region. Seasonal variation in phenolic contents in healthy and galled leaves detected in A. spruceanum was primarily related to abiotic conditions. Even though the levels of phenolic contents might get a maximum of 10 mg EAT g-1, which indicated a non stimulating cell chemical environment to gall induction and herbivore survivorship, A. spruceanum gall maker surpassed this chemical barrier, and might also be favored by the chemical protection against its natural enemies, that phenolic contents might confer