Effect of stem structural characteristics and cell wall components related to stem lodging resistance in a newly identified mutant of hexaploid wheat (Triticum aestivum L.)

In wheat, lodging is affected by anatomical and chemical characteristics of the stem cell wall. Plant characteristics determining the stem strength were measured in lodging tolerant mutant (PMW-2016-1) developed through mutation breeding utilizing hexaploid wheat cultivar, DPW-621-50. Various anatomical features, chemical composition, and mechanical strength of the culms of newly developed lodging-tolerant mutant (PMW-2016-1) and parent (DPW-621-50), were examined by light microscopy, the Klason method, prostate tester coupled with a Universal Tensile Machine, and Fourier Transform Infrared Spectroscopy. Significant changes in the anatomical features, including the outer radius of the stem, stem wall thickness, and the proportions of various tissues, and vascular bundles were noticed. Chemical analysis revealed that the lignin level in the PMW-2016-1 mutant was higher and exhibited superiority in stem strength compared to the DPW-621-50 parent line. The force (N) required to break the internodes of mutant PMW 2016-1 was higher than that of DPW-621-50. The results suggested that the outer stem radius, stem wall thickness, the proportion of sclerenchyma tissues, the number of large vascular bundles, and lignin content are important factors that affect the mechanical strength of wheat stems, which can be the key parameters for the selection of varieties having higher lodging tolerance. Preliminary studies on the newly identified mutant PMW-2016-1 suggested that this mutant may possess higher lodging tolerance because it has a higher stem strength than DPW-621-50 and can be used as a donor parent for the development of lodging-tolerant wheat varieties

Somatic Embryogenesis and Plant Regeneration in Viola canescens Wall. Ex. Roxb.: An Endangered Himalayan Herb

Viola canescens Wall. ex. Roxb. is an important but threatened medicinal herb found at 1500–2400 m above mean sea level in the Himalayas. Overexploitation and habitat preference have put the plant under serious threat. Thus, the present study was undertaken to develop an efficient protocol for in vitro propagation via somatic embryogenesis. The results revealed that plant can be regenerated successfully through somatic embryogenesis using leaf derived calli. Regular subculturing of calli on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D)/indole-3-butyric acid (IBA)/kinetin (Kn) and varying combinations of 2,4-D+Kn induced somatic embryogenesis. The maximum average number of somatic embryos (SE) (19.15 ± 2.66) was induced on the medium with 0.15 + 0.05 mg L−1 of 2,4-D and Kn, respectively, and this medium was used as a control. To enhance somatic embryo induction, the control MS medium was supplemented with l-glutamine (200–400 mg L−1) and casein hydrolysate (1–4%). The maximum average number of SE (27.66 ± 2.67) and average mature SE (13.16 ± 3.48) were recorded on the medium having 2 % l-glutamine and 50 mg L−1 casein hydrolysate. The induced SE were asynchronous, so, to foster their maturation, the culture medium (free from growth regulators) was supplemented with abscisic acid (ABA) and silver nitrate (AgNO3). The maximum average number (35.96 ± 3.68) of mature SE was noticed on MS medium supplemented with 1.5 mg L−1 ABA. Mature embryos had two well-developed cotyledons and an elongated hypocotyl root axis. The development of SE into plantlets was significant for embryos matured on the medium with AgNO3 and ABA, with 86.67% and 83.33% conversion on the medium with 0.20 mg L−1 6-benzylaminopurine (BAP). The plantlets thus produced acclimatized in a growth chamber before being transferred to the field, which showed 89.89% survival. The plants were morphologically similar to the mother plant with successful flowering