Iron formulation affects in vitro storage of hops: An image analysis

Abstract

SummaryIn vitro-stored plant germplasm is usually evaluated by visual analysis of the plant based on subjective characters. To reduce the variability in these evaluations, we developed a digital-image evaluation system for in vitro-stored plantlets. This study compares the standard visual evaluation system with a digital analysis system to determine if digital analysis can effectively quantify the health of diverse Humulus germplasm. Eight cultivars of Humulus lupulus L. were stored on standard Murashige and Skoog (MS) medium with iron alone (EDTA chelated) and on MS iron with 100 or 200 mg l 21 sequestrene 138 iron (EDDHA chelated). Digital images of the upper two nodes of each plantlet were evaluated for red, green, blue, green/red ratio, and modified normalized difference vegetation index (MNDVI ¼ R 2 G/R þ G). Evaluation of each plantlet for MNDVI values showed consistent significant differences for all treatments only at the upper node. Significant differences for visual and the MNDVI values among the three iron treatments were observed at the upper node of most of the eight hop cultivars. Regression analysis of the upper node MNDVI values vs. whole-plant visual ratings showed positive correlations for most cultivars. Effects of iron treatments on storage duration were also analyzed for both visual and digital systems. There were significant differences among MNDVI values for plantlets stored on medium with standard MS iron alone (EDTA chelated) and with the addition of sequestrene 138 iron. In general, the MNDVI value of the upper node correlated well with visual ratings and could be used to determine the health of in vitro stored hops.

Use of regression analysis in plant cell, tissue, and organ culture experiments

“…Some recent references have applied regression analyses to explain biological responses (Aynalem et al 2006;Mokhtassi et al 2006;Onyeka et al 2006;Sharma et al 2006;Zhu et al 2006;Browne 2007). In our opinion, only Onyeka et al (2006) and Zhu et al (2006) demonstrated that regression contributed to clarity of their biological results.…”

“…Therefore, data dispersion could not be observed. Aynalem et al (2006) estimated straight line functions, but some R 2 were as low as 0.40 and consequently the regression functions did not fit the data properly. Browne (2007) also estimated straight line functions but determination coefficients were extremely low (0.12 and 0.27).…”

Vegetative propagation of hops (Humulus lupulus L.): Historical approach and perspectives

“…Simple microcuttings were immersed in the encapsulating solution (AE enriched with sodium alginate at 2.5% (w/v) sodium salt of alginic acid) with medium viscosity and, subsequently, the alginate-coated propagules were immersed in Plant germplasm stored in vitro is usually evaluated by visual analysis based on subjective characters, which decreases accuracy. Aynalem et al (2006) developed a digital image assessment system for H. lupulus L. stored in vitro to reduce variability in these assessments. The cultivars were stored in standard MS medium with iron (chelated EDTA) and MS medium with 100 or 200 mg L −1 of Sequestrene 138 iron (chelated EDDHA).…”

The use of biotechnology in hop (Humulus lupulus L.) improvement

“…In vitro techniques have been found to be useful in ex situ conservation of a number of plant species (VILLALOBOS and ENGELMANN, 1995), including meristem culture-derived virus-free germplasms (FLETCHER et al, 1998). The storage longevity of in vitro collections depends on many important factors such as explant type, culture medium composition and culture conditions (AYNALEM et al, 2006;FARAGÓ et al, 2008) According to REED et al (2003) the U.S. Department of Agriculture, ARS, National Clonal Germplasm Repository at Corvallis (Oregon, USA) maintains about 700 accessions of Humulus spp. germplasm in field collections, in pots in the screen house, and as tissue cultures in cold storage or as cryopreserved shoot tips in liquid nitrogen.…”