The prevalence of vitamin A deficiency in sub-Saharan Africa necessitates effective approaches to improve provitamin A content of major staple crops. Cassava holds much promise for food security in sub-Saharan Africa, but a negative correlation between β-carotene, a provitamin A carotenoid, and dry matter content has been reported, which poses a challenge to cassava biofortification by conventional breeding. To identify suitable material for genetic transformation in tissue culture with the overall aim to increase β-carotene and maintain starch content as well as better understand carotenoid composition, root and leaf tissues from thirteen field-grown cassava landraces were analyzed for agronomic traits, carotenoid, chlorophyll, and starch content. The expression of five genes related to carotenoid biosynthesis were determined in selected landraces. Analysis revealed a weak negative correlation between starch and β-carotene content, whereas there was a strong positive correlation between root yield and many carotenoids including β-carotene. Carotenoid synthesis genes were expressed in both white and yellow cassava roots, but phytoene synthase 2 (PSY2), lycopene-ε-cyclase (LCYε), and β-carotenoid hydroxylase (CHYβ) expression were generally higher in yellow roots. This study identified lines with reasonably high content of starch and β-carotene that could be candidates for biofortification by further breeding or plant biotechnological means.

中文翻译：

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十三种尼日利亚木薯地方品种的基因表达和代谢谱分析，以阐明淀粉和类胡萝卜素成分

撒哈拉以南非洲地区普遍存在维生素A缺乏症，因此有必要采取有效措施来提高主要主粮作物中维生素A的含量。木薯在撒哈拉以南非洲的粮食安全方面具有广阔的前景，但据报道β-胡萝卜素，维生素原A类胡萝卜素与干物质含量之间呈负相关，这对常规育种对木薯生物强化构成了挑战。为了确定适合组织培养中遗传转化的材料，其总体目标是增加β-胡萝卜素并保持淀粉含量，并更好地了解类胡萝卜素的组成，分析了十三种田间种植的木薯地方品种的根和叶组织的农艺性状，类胡萝卜素，叶绿素和淀粉含量。在选定的地方品种中确定了与类胡萝卜素生物合成相关的五个基因的表达。分析表明，淀粉与β-胡萝卜素含量之间呈弱负相关，而根产量与包括β-胡萝卜素在内的许多类胡萝卜素之间呈强正相关。类胡萝卜素合成基因在白色和黄色木薯根中均有表达，但八氢番茄红素合酶2（PSY2），番茄红素-ε-环化酶（LCYε）和β-类胡萝卜素羟化酶（CHYβ）的表达在黄根中通常较高。这项研究确定了淀粉和β-胡萝卜素含量较高的品系，可以通过进一步育种或植物生物技术手段进行生物强化。