An update on the maize zein-gene family in the post-genomics era

Abstract

Maize (Zea mays) is a cereal crop of global food importance. However, the deficiency of essential amino acids, more importantly lysine, methionine and tryptophan, in the major seed storage zein proteins makes corn nutritionally of low value for human consumption. The idea of improving maize nutritional value prompted the search for maize natural mutants harboring low zein contents and higher amount of lysine. These studies resulted in the identification of more than dozens of maize opaque mutants in the previous few decades, o2 mutant being the most extensively studied one. However, the high lysine contents but soft kernel texture and chalky endosperm halted the widespread application and commercial success of maize opaque mutants, which ultimately paved the way for the development of Quality Protein Maize (QPM) by modifying the soft endosperm of o2 mutant into lysine-rich hard endosperm. The previous few decades have witnessed a marked progress in maize zein research. It includes elucidation of molecular mechanism underlying the role of different zein genes in seed endosperm development by cloning different components of zein family, exploring the general organization, function and evolution of zein family members within maize species and among other cereals, and elucidating the cis-and trans-regulatory elements modulating the regulation of different molecular players of maize seed endosperm development. The current advances in high quality reference genomes of maize lines B73 and Mo17 plus the completion of ongoing pan genome sequencing projects of more maize lines with NGS technologies are expected to revolutionize maize zein gene research in near future. This review highlights the recent advances in QPM development and its practical application in the post genomic era, genomic and physical composition and evolution of zein family, and expression, regulation and downstream role of zein genes in endosperm development. Moreover, recent genomic tools and methods developed for functional validation of maize zein genes are also discussed.

Bacterial endophytes inhabiting desert plants provide protection against seed rot caused by Fusarium verticillioides and promote growth in maize

“…Maize has economic importance as a food crop for human, animal consumption, industrial and pharmaceutical purposes worldwide. 1 Maize crops are susceptible to diseases, particularly those caused by pathogenic fungi, of which Fusarium maize ear, kernel, and root rot diseases are caused by Fusarium verticillioides. The latter is the most important and the most reported worldwide and in Cameroon.…”

Progressive Aggregation of 16 kDa Gamma-Zein during Seed Maturation in Transgenic Arabidopsis thaliana

“…Zeins, the prolamins of maize ( Zea mays ), can be divided into four classes: alpha (more than thirty genes), gamma (three genes that produce polypeptides of 27, 50, and 16 kDa), beta (a single gene), and delta (two genes that encode for 10 kDa and 18 kDa polypeptides) [ 10 , 11 ]. Alpha and delta zeins constitute the core of the PB, whereas 27 kDa and 50 kDa gamma zeins (27γz, 50γz) form the outer PB layer, in contact with the luminal face of the ER membrane, and 16 kDa gamma zein (16γz) is at the interface between the inner core and outer PB layer [ 2 , 12 ].…”

Maize significance in Indian food situation to mitigate malnutrition

“…In general, maize protein has been named as zein. Zein proteins constitute more than 60% of the total stored proteins in the maize kernel (Khan et al., 2019). On the basis of physical composition, zein proteins are classified into four subfamilies.…”

“…Further, zeins are broadly categorized into two groups based on the amino acid composition such as zein1 and zein2. Zein1 group includes two α‐zeins proteins and zein2 group contains six different δ, β, and γ zeins (Khan et al., 2019). Extensive research has been conducted on the biofortification of maize with different nutrients.…”