RT-qPCR has been widely used for gene expression analysis in recent years. The accuracy of this technique largely depends on the selection of suitable reference genes. In order to facilitate gene expression analysis in wild and cultivated Cannabis, the expression stability of seven candidate reference genes (ACT2, 18S rRNA, GAPDH, UBQ, TUB, PP2A and EF1α) were assessed in leaves samples of different development stages and different organs of both wild and cultivated Cannabis in the present study. Their expression stabilities were evaluated through three software packages (GeNorm, Normfinder and Bestkeeper). Results showed that UBQ and EF1α were the highly ranked genes in different leaves samples, and PP2A was the most stable reference gene in different organs, while GAPDH was the least stable one. And the validation of the reference genes selected was further confirmed by the expression patterns of MDS and OLS. Expression levels of 7 reference genes in Cannabis, presented as mean value of Ct in all 20 conditions. Ct values are the average of three replicates.

In this study, we identified a novel partitivirus infecting industrial hemp (Cannabis sativa L.), named as industrial hemp cryptic virus (IHCV). The complete genome sequence of IHCV comprises two RNA segments: dsRNA1 (1683 nt) encoding an RNA-dependent RNA polymerase (RdRp, 481 aa), and dsRNA2 (1669 nt) encoding a coat protein (CP, 417 aa). Comparative sequence analyses revealed that RdRp shares 68.10% amino acid similarity with the Citrullus lanatus cryptic virus (CiLCV), while the CP exhibits 35.80% similarity with the vitis cryptic virus (VCV). Moreover, phylogenetic analysis showed that both the RdRp and CP proteins of IHCV clustered together with the pepper cryptic virus 1 (PCV1), which belongs to the genus Deltapartitivirus. Seeds detection assays revealed seed infection rates ranging from 20% to 90% among different industrial hemp cultivars. This is the first report of a novel partitivirus virus infecting industrial hemp.

Industrial hemp is a crop with a high tolerance and accumulation of lead (Pb). Improving the Pb tolerance and accumulation capacity of industrial hemp is of great scientific and practical importance. This study utilized a pot with soil contaminated with Pb to investigate the differences in Pb tolerance between two industrial hemp varieties, Yunma1 (YM) and Shaanxi Industrial Hemp (SM), under Pb stress. The results indicated that Pb mainly accumulates in the roots of YM and SM (70–80%), with YM having a higher Pb accumulation than SM. It is worth nothing that under high Pb concentration conditions (5000 mg/kg), the Pb accumulation capacity of YM is twice that of SM. Accumulation characteristics of Pb in different plant tissues followed the pattern: roots > stems > leaves > fibers > seeds. In YM, approximately 70% of the absorbed Pb was fixed in the roots and 30% was transported to the above-ground parts. In contrast, SM transported more than 50% of absorbed Pb by roots to the above-ground areas, causing some degree of damage to stems and leaves. Even when Pb concentrations exceed 4000 mg/kg, YM exhibits strong tolerance (tolerance index greater than 90%), with normal growth and no signs of toxicity. However, SM showed a tolerance level of < 50% at high Pb concentrations, with significant heavy metal toxicity symptoms in the above-ground areas. These results provide important information for the remediation of Pb contaminated soils in mining areas.