Introgression of low phytic acid locus (lpa2-2) into an elite Maize (Zea mays L.) inbred through marker assisted backcross breeding

Abstract Phytic Acid (PA) in maize kernel is an anti-nutritional factor; it chelates mineral cations in human gut and causes mineral deficiency in humans. Therefore, development of low-PA maize is required. Here, we have transferred the low-PA locus (i.e., lpa2-2 allele that confers low-PA trait) by crossing low-PA line "EC 659418" (donor line) with an elite inbred "UMI 285" (recipient line) using Marker Assisted Backcross Breeding (MABB). In our MABB program, for "foreground selection" (i.e., screening for plants with introgressed lpa2-2 locus) small sequence repeat (SSR) marker "umc2230" was used, and for "background selection" (i.e., screening for introgressed lines whose genetic background are similar to that of the recurrent parent) 47 SSR markers were used. As a result, we have developed four lines with both reduced-PA trait similar to that of donor parent, and agronomical traits (i.e., days to 50% tasseling, days to 50% silking, plant height, ear height, 100 seed weight, grain yield per plant, germination and seed vigor) similar to that of the recurrent parent

The Cac2 subunit is essential for productive histone binding and nucleosome assembly in CAF-1

Nucleosome assembly following DNA replication controls epigenome maintenance and genome integrity. Chromatin assembly factor 1 (CAF-1) is the histone chaperone responsible for histone (H3-H4)2 deposition following DNA synthesis. Structural and functional details for this chaperone complex and its interaction with histones are slowly emerging. Using hydrogen-deuterium exchange coupled to mass spectrometry, combined with in vitro and in vivo mutagenesis studies, we identified the regions involved in the direct interaction between the yeast CAF-1 subunits, and mapped the CAF-1 domains responsible for H3-H4 binding. The large subunit, Cac1 organizes the assembly of CAF-1. Strikingly, H3-H4 binding is mediated by a composite interface, shaped by Cac1-bound Cac2 and the Cac1 acidic region. Cac2 is indispensable for productive histone binding, while deletion of Cac3 has only moderate effects on H3-H4 binding and nucleosome assembly. These results define direct structural roles for yeast CAF-1 subunits and uncover a previously unknown critical function of the middle subunit in CAF-1.</p